Figure 1. Fish swimming modes. Swimming by body and caudal fin movements becomes more concentrated toward the tail with a shift from undulation to oscillation. Appendicular swimming is associated with use of the dorsal and anal fins, a combination of both fins, and the pectoral fins. Shaded areas represent body regions and fins used for propulsion.

Figure 2. Instabilities. Rotation about the longitudinal, transverse and vertical axes of a fish leads to instabilities in roll, pitch and yaw, respectively.

Figure 3. Morphological specializations associated with swimming performance. Tuna are specialized for cruising, pike for acceleration, and butterfly fish for manoeuvrability. The generalist (e.g. bass) is a morphological compromise of the disparate specialized forms.